1. Field of the Invention
This invention relates to a scaffolding system for use on an inclined surface, such as inside a ship cargo hold.
2. Description of Related Art
A large segment of the maritime transport business involves the bulk shipment of cargoes in motor vessels with open top holds. These cargoes range from edible products such as wheat, soya, corn, etc. to the inedible, such as iron ore, coal, fertilizer, chemicals etc. The holds range in depth from 30 to over 75 feet. Because of the limited number of vessels available to carry bulk cargoes, a ship may carry coal on one voyage and grain on the next. However, before a ship can load grain at any grain elevator in the United States, its holds must be inspected for cleanliness by representatives of the U.S. Department of Agriculture and the National Cargo Bureau. If contaminants, such as rust, paint scale or residue from the previous cargo are found, the ship must be cleaned before it will be allowed to proceed to berth and load its cargo.
While a vessel is being cleaned, it is not ready to load cargo. A day when a vessel is not ready to load cargo is referred to as a "lay day." Each lay day represents revenue lost to the vessel owners and operators. The cleaning of the ship incurs significant additional cost. Cleaning a seven-hold ship in the manner required to pass cargo loading inspections can require three lay days, and cost of more than $80,000. Vessel owners and operators have tried to cut these costs by using the ship's crew to clean the holds while the ship is in transit to the grain elevator. However, the only equipment conventionally available to the crew for reaching the higher areas in the cargo holds are ladders. Because of the pitching and rolling of the ship as it passes through open seas, only short ladders can be safely used. Additionally, once in port, and having failed the inspection, the crews often have neither the time nor the equipment to quickly and efficiently correct the inspection discrepancies. As a result, shore cleaners are called in to do the required cleaning.
The use of conventional scaffolding within a ship hold while the ship is in transit is impractical for the following reasons. Conventional scaffolding must rest on a flat surface. With the pitching of the deck, conventional scaffolding becomes unstable. Because conventional scaffolding must rest on a flat surface, it is prevented by the "hoppers" from getting close to the bulkheads. Conventional scaffolding is made from steel, and, consequently, is heavy. Several classes of ship have no deck gear for lowering equipment into the cargo holds. For such classes of ship it is difficult, if not impossible, to use conventional steel scaffolding for cleaning the cargo holds. Additionally, conventional steel scaffolding covers only ten (10) lineal feet of area to be cleaned per set-up. Each set-up takes approximately four hours. At such a rate there is not enough transit time to complete the cleaning for a typical cargo ship. Consequently, the use of conventional scaffolding is an impractical option for cleaning cargo holds while the ship is in transit.
A scaffolding system that takes less time to erect is described in U.S. Pat. No. 4,598,794 to Anderson. The Anderson patent describes a pump jack scaffolding system, employing pump jacks and pump jack poles. Workers stand on scaffolding staging, which is supported by support arms that project from the pump jacks, and operate the pump jacks to move the staging up and down along the pump jack poles. The scaffolding described in the Anderson patent is erected more simply and quickly than conventional scaffolding. However, the scaffolding system described in the Anderson patent is inoperable in an environment having an inclined or sloping surface, such as a cargo hold of a ship. Additionally, the scaffolding system described in the Anderson patent is not configured for a moving environment, such as when a ship is at sea. The scaffolding system of the Anderson patent does not provide the support needed to stabilize the scaffolding system against the movement of the ship.
Thus, there is a need for a scaffolding system that can be used on an inclined surface and in a moving environment. There is a need for a scaffolding system that enables ship crews to safely and efficiently clean cargo holds while underway.